The contemporary design of internal combustion engines must cope with the increasingly stringent regulations on pollutant emissions. Accordingly, automotive engineers strive for designing engines with low fuel consumption and low emission of pollutants, which implies including electronic devices capable of monitoring the combustion performance and emissions in the exhaust gases.
In this connection, a proper operation of a fuel-injected engine requires that the fuel injectors and their controller allow for a timely, precise and reliable fuel injection. Indeed, it is well known that problems arise when the performance, or more particularly the timing, and the quantity of fuel delivered by the injectors diverge beyond acceptable limits. For example, injector performance deviation or variability will cause different torques to be generated between cylinders due to unequal fuel amounts being injected, or from the relative timing of such fuel injection. And this problem is particularly acute when injecting small fuel quantities, due to response delays at opening and closing.
In order to take into account the specificities of a solenoid actuated fuel injector, it has been proposed to associate to a given fuel injector a number of performance parameters thereof. These performance parameters are, e.g., encoded in a bar code applied to the injector, so that the performance parameters can be retrieved by a bar code scanner at the time of installation in the engine and transferred to the engine control unit (ECU). Such method for fuel injector parameters installation is for example described in U.S. Pat. No. 7,136,743.
Another method of fuel injector installation has been disclosed in WO2011/073147, which uses a segmented master performance curve. Each fuel injector to be installed in the engine is provided with specific fuel injector parameters in a machine-readable format, and these parameters are transferred to the engine ECU. Fitting information, preferably coefficients for a characteristic equation attributed to each respective segment of the master flow curve, are contained in these fuel injector-specific parameters.
The above method is beneficial in that it allows appropriately describing the flow performance per injector and provides finer control in the ballistic operating range. However, the ballistic range is a critical operating region and it has appeared that the above method may, under certain conditions, not discriminate cases where the injector does not open.
It is desirable to provide a method of controlling fuel injection in an internal combustion engine that avoids the above disadvantage.